Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this disclosure and are not admitted to be prior art by inclusion in this section.
Recently, due to the rapid growth of smart phone penetration, data traffic in the mobile network is experiencing explosive growth. Among all types of mobile data traffic, streaming is one important part. According to a report, by the end of the first quarter of 2011, video traffic accounts for 39% of the mobile data traffic. Besides, according to a forecast, video streaming may account for about 70% of the mobile data traffic at 2016. Along this trend, several streaming delivery approaches have been deployed and studied. Among all the methods, P2P is one important approach to deliver streaming content over networks. Some P2P based live streaming systems have been used in context of fixed access networks, such as PPlive and PPstream.
However, the existing P2P streaming system used in fixed networks would face some serious problems when it comes to mobile networks. For example, from a mobile terminal aspect, UL transmission from the mobile terminal is much more power consuming as compared with DL reception, and a mobile terminal is usually power constrained due to its limited battery capacity and movement. Furthermore, UL bandwidth of typical 3GPP mobile networks is usually more limited as compared with that of DL. On the other hand, typical P2P systems basically depend on UL contribution from peers. Therefore, a potential topic is how to optimize P2P live streaming by considering specific characteristics and restrictions of the mobile network/mobile terminal, as well as to resolve the churn of P2P live streaming in the mobile network.
To facilitate the understanding of problems of P2P live streaming over mobile networks. The basic architecture and principles of the PPlive streaming are introduced by referring to FIG. 1 (see Reference 1).
FIG. 1 illustrates a basic architecture of a PPlive streaming system. Generally, there are one channel streaming server and one tracker server as P2P infrastructure fundamental elements for a PPlive streaming system. To boost performance of the P2P streaming system, one or more super nodes may be deployed as well. A streaming peer node includes a streaming engine and a media player co-located in the same machine. All peers cooperatively deliver video chunks among themselves from the channel streaming server via the streaming engine. The channel stream server converts media content into small video chunks for efficient distribution among peers. The tracker server provides streaming channel, peer and chunk information for each peer node to join the network and download video chunks from multiple peers in the system requesting the same media content.
So far, there are already a couple of academic studies on the typical P2P live streaming system in both of the fixed and wireless environments. Here, results from a previous study (see Reference 2) on P2P live streaming systems (e.g., PPlive, PPstream, SopCast, QQstream) are indicated to explain the problem by referring to the following Table 1 and FIG. 2, FIG. 3 and FIG. 4 together.
TABLE 1Summary of Statistics on LaptopEncodingTotal #Total # ofTotal # ofSleepAverage #Rateof IPControlStreamingTimeofNameArchitecture(Kbps)PacketsPacketsPackets(%)NeighborsPPTVP2P400191716116819708734.4212PPSP2P396433935322779851800.0920SopCastP2P530305826202240924570.993QQLiveP2P5002934741838141088277.124J.tvC/S433123655566896696621.44N/A
Key observations from the previous study are as follows:                A P2P streaming peer needs to transmit an extremely large number of C-plane small packets which account for more than 60%. Besides, C-plane and U-plane packets are usually transmitted together.        The amount of uploading traffic from a peer to its neighbors changes dynamically from 10 Kbps to over 1.5 Mbps. The UL/DL traffic ratio is about 1:1 for PPTV and 5:3 for PPS.        A client in P2P streaming receives packets from dynamically changing sources (e.g., 3 to 20 peers). More peers usually mean more C-plane traffics and more UL U-plane traffics.        
So a new mechanism is needed when establishing a P2P streaming system over a mobile network.